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Help with voltage step-down (I am very much a beginner)

bsavitch

Nov 25, 2020
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Hello,

I'm attempting to make my son a lightsaber and need some help. I have an old cheap toy lightsaber powered by 3 AA batteries (1.5V each) in series. The toy has a board that controls a small LED and sound board when powered on.

I bought some LED strip lighting to use in the new saber- advertised as 12V, but I have it working with a 9V battery. Anyway, I would like to use the existing board to function with the new LED strip lighting, but don't really know how to do that. I have a bunch of various resistors that I took from some other small electronics. I'm honestly not sure where to start.

I would happily post pictures of what I have if that would help. I greatly appreciate any help or guidance.

Thanks,
Brian
 

Martaine2005

May 12, 2015
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Hi Brian, I think you will need to upload some very clear photos of the items you have.
So, you have two Sabers?
1 runs off 3x1.5v batteries =4.5v.
And 1 that runs from 12v?.
The LED strip is 12v.

Personally, you would be better off getting a LED strip that runs from USB, ie 5v to use with the older saber.

If I understand correctly, you can’t step down the voltage for the LED strip. It already has resistors along the strip length.
It may run from a 9v battery but current draw may render the battery useless after a short time.

Martin
 

bsavitch

Nov 25, 2020
4
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Hi Brian, I think you will need to upload some very clear photos of the items you have.
So, you have two Sabers?
1 runs off 3x1.5v batteries =4.5v.
And 1 that runs from 12v?.
The LED strip is 12v.

Personally, you would be better off getting a LED strip that runs from USB, ie 5v to use with the older saber.

If I understand correctly, you can’t step down the voltage for the LED strip. It already has resistors along the strip length.
It may run from a 9v battery but current draw may render the battery useless after a short time.

Martin

Hi Martin - I think I didn't explain it very well.
I have one saber that I've taken apart. I'm making a new one. I took the electronics out of the old one. Basically, I want it to do everything it's already doing, except instead of powering the small light that it came with, I want it to power my new LED strip. So I think I need more voltage at the light, but then the voltage to power the soundboard/speaker needs to be stepped down. I have some resistors that I've removed from other electronics that I can use if they could help at all.

See pictures...
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bertus

Moderator
Nov 8, 2019
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Hello,

The pictures don't show.
Shrink the pictures to about 300 kB and post them over here using the "Upload a File" button.

Bertus
 

Martaine2005

May 12, 2015
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As @bertus said, resize the images.
I think I now understand. But still think the 5v strip would have suited better to your application.

Martin
 

bsavitch

Nov 25, 2020
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OK - Photos should be attached this time...
 

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Martaine2005

May 12, 2015
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Do you have the specifications of the LED strip?
What length will you use from the strip?

Martin
 

bsavitch

Nov 25, 2020
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Nov 25, 2020
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IP65, 12V Waterproof Flexible LED Strip Light(Power Cord not Included), 16.4ft/5m Cuttable LED Light Strips, 300 Units 3528 LEDs Lighting String.

They recommend a 12v 2amp power supply. I plan to use approximately 6 feet of the LED strip.

Is there any way to make this work? I'd really rather not get another LED strip.

Thanks,
Brian
 
Last edited by a moderator:

Martaine2005

May 12, 2015
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The strip you have and the original module board are not going to work.
It might be possible with boost converter and or a mosfet/relay. But the 3 AA batteries won’t last five minutes.

Martin
 
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